The present invention relates to a device for stacking sheet material so as to form individual stacks which are each comprised of a preselected number of sheets, whereby the number of sheets successively delivered and conveyed onto an individual stack by means of conveying rollers is kept constant for each stack and the individual stacks are piled up to form a full stack.
For stacking sheet material cut to a specific size, such as, for example, metal plates or sheets of paper or other materials, it is known, prior to depositing a stack of sheet material, to insert two cardboard sheets of the same size as an intermediate layer and then to stack these intermediate sheets together with the cut-to-size sheets of material. The cardboard sheets mark the individual stacks and divide the full stack into individual stacks, thus facilitating the production of individual packs comprising a certain number of sheets from the full stack.
In particular, for dividing stacks of paper into individual stacks comprising 1,000 sheets, which are commonly referred to as reams, it is usual to mark the individual stacks by inserting strips of material between them, whereby the portions of the strips which protrude from the stacks are bent downwardly and closely adjoin the stack surface. It is a disadvantage that the loosely inserted strips often slip out of the stack, so that the ream marking is lost and, moreover, the slipped-out strips may impede the sheet stacking process.
German Offenlegungsschrift 29 02 261 discloses a process for marking reams comprising a predetermined number of sheets, where the sheets which are sequentially delivered onto the stack are counted and the ream is marked when the preselected number of sheets is reached. For this purpose, the counter pulses are stored and when the stacking of the preselected number of sheets is completed, a stamping device is activated, by which the head end of the upper portion of the ream is ink-marked, the stamp print gradually fainting in the downward direction and the lowest portion of the respective ream remaining free from ink. The device for performing this process comprises a stamp which is arranged at the head end of the sheet stacking device and is angularly fastened to a rod which can be moved to and fro.
German Offenlegungsschrift 26 22 781 describes a device for removing a ream consisting of a preselected number of sheets from a pile of sheet-like material. This device comprises a vertically and horizontally displaceable, table-like platen which can be introduced into the pile in the horizontal direction and which, at its front edge which is to be inserted into the pile, is provided with a rotating roller by which the pile is spread. During the insertion of the table-like platen into the stack the advance speed of the platen and the circumferential speed of the roller are substantially identical. Over a portion of its length, the table-like platen is conically reinforced, the reinforced portion starting at the front edge and extending away from the roller. At the end of the conically reinforced portion a second roller is provided in the surface of the table-like platen, in parallel alignment with the first roller and at a distance therefrom. The circumferential speed of the second roller essentially corresponds to the circumferential speed of the first roller and the advance speed of the table-like platen.
The foregoing illustrates limitations known to exist in present devices. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.